This is a National Institutes of Environmental Health Services-sponsored five-year multicenter study of the effects of chelation with succimer on growth and development of children with low levels of blood lead. The specific aims of the study are 1) to determine if young children with low but elevated levels of blood lead will benefit from oral chelation treatment with succimer as measured by developmental testing at three years after initiation of therapy and 2) to determine if such chelation affects the growth parameters and blood pressure over a three year period. Thirty-two patients have completed the study protocol and are now in the follow-up phase during which blood lead levels are monitored every three to four months. Forty-four patients are still receiving study drug. Recruitment will continue through 1996 and into early 1997.